Use of dying gasp to locate faults in communications networks

ABSTRACT

Novel tools and techniques that can be used to detect network impairment, including but not limited to impairment of optical fiber networks. In an aspect, such tools and techniques can be deployed at relatively low cost, allowing pervasive deployment throughout a network. In another aspect, such tools and techniques can take advantage of a “dying gasp,” in which a network element detects a sudden drop in received optical (or electrical) power, resolution, etc. at short time scales and sends a notification across the network before the connection is completely compromised. In yet another aspect, some tools can include a supervisory function to analyze aspects of the dying gasp with the goal to determine network segments associated with an impairment and an estimate of the location of an impairment within the network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/582,535, filed Dec. 24, 2014 by Fargano et al. and entitled, “Use ofDying Gasp to Locate Faults in Communications Networks”, which is acontinuation of U.S. patent application Ser. No. 13/928,069 (now U.S.Pat. No. 8,948,587), filed Jun. 26, 2013 by Fargano et al. and entitled,“Use of Dying Gasp to Locate Faults in Communications Networks”, whichclaims the benefit, under 35 U.S.C. §119, to provisional U.S. PatentApplication No. 61/665,182, filed Jun. 27, 2012 by Fargano et al. andentitled “Use of Dying Gasp to Locate Fiber Faults in Passive OpticalNetworks” and provisional U.S. Patent Application No. 61/787,690, filedMar. 15, 2013 by Fargano et al. and entitled “Use of Dying Gasp toLocate Faults in Communication Networks”, the entire disclosures of eachare incorporated herein by reference.

BACKGROUND

The current state of the art for fiber impairment isolation requiresdedicated equipment, commonly referred to as Optical Time DomainReflectometers (“OTDRs”) to send short laser pulses into an opticalfiber, with the goal of detecting reflections from discontinuities suchas connectors, splice points, kinks, sharp bends, fiber faults, etc.Current OTDRs are costly precision instruments and allow detection offiber discontinuities to within a few meters or less.

This dedicated equipment is expensive to deploy, however, and thereforeis difficult to use in a preventative capacity. Hence, there is a needfor impairment detection solutions that can be deployed at lower costthroughout a network.

SUMMARY

A set of embodiments provides tools and techniques that can be used todetect network impairment, including but not limited to impairment ofoptical fiber networks. In an aspect, such tools and techniques can bedeployed at relatively low cost, allowing pervasive deploymentthroughout a network. In another aspect, such tools and techniques cantake advantage of a “dying gasp,” in which a network element detects asudden drop in received optical (or electrical) power, resolution, etc.at short time scales and sends a notification across the network beforethe connection is completely compromised. As another aspect, someembodiments can include a supervisory function to analyze aspects of thedying gasp with the goal to determine network segments associated withan impairment and an estimate of the location of an impairment withinthe network.

The tools provided by various embodiments include, without limitation,methods, systems, and/or software products. Merely by way of example, amethod might comprise one or more procedures, any or all of which areexecuted by a computer system. Correspondingly, an embodiment mightprovide a computer system configured with instructions to perform one ormore procedures in accordance with methods provided by various otherembodiments. Similarly, a computer program might comprise a set ofinstructions that are executable by a computer system (and/or aprocessor therein) to perform such operations. In many cases, suchsoftware programs are encoded on physical, tangible and/ornon-transitory computer readable media (such as, to name but a fewexamples, optical media, magnetic media, and/or the like).

Merely by way of example, one set of embodiments provides methods,including without limitation methods of estimating a location of animpairment in a network. In a particular embodiment, the network mightbe an optical network, such as a passive optical network (“PON”), toname one example of many.

An exemplary method might comprise receiving (e.g., at a computersystem) one or more dying gasp communications. In an aspect, the one ormore dying gasp communications might comprise at least one communicationfrom a network element in the optical network. The method might furthercomprise determining, with the computer system, based at least in parton the one or more dying gasp communications, that a network impairmenthas occurred. In some embodiments, the method can also includeidentifying, with the computer system, based at least in part on the oneor more dying gasp communications, an approximate location of thenetwork impairment.

Another set of embodiments provides apparatus. An exemplary apparatusmight comprise a non-transitory computer readable medium having encodedthereon a set of instructions executable by one or more computers toperform one or more operations, including without limitation operationsin accordance with methods provided by other embodiments. Merely by wayof example, the set of instructions might comprise instructions toreceive one or more dying gasp communications, which might include atleast one communication from a network element in a network. The set ofinstructions might further comprise instructions to determine, based atleast in part on the one or more dying gasp communications, that anetwork impairment has occurred, and/or instructions to identify, basedat least in part on the one or more dying gasp communications, anapproximate location of the network impairment.

A further set of embodiments provides systems, including withoutlimitation computer systems. An exemplary system might comprise one ormore processors and/or a non-transitory computer readable medium incommunication with the one or more processors. In an aspect, thecomputer readable medium can have encoded thereon a set of instructionsexecutable by the computer to perform one or more operations, includingwithout limitation operations in accordance with methods provided byother embodiments. For instance, the set of instructions might compriseinstructions to receive one or more dying gasp communications, whichmight include at least one communication from a network element in anetwork. The set of instructions might further comprise instructions todetermine, based at least in part on the one or more dying gaspcommunications, that a network impairment has occurred, and/orinstructions to identify, based at least in part on the one or moredying gasp communications, an approximate location of the networkimpairment.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of particularembodiments may be realized by reference to the remaining portions ofthe specification and the drawings, in which like reference numerals areused to refer to similar components. In some instances, a sub-label isassociated with a reference numeral to denote one of multiple similarcomponents. When reference is made to a reference numeral withoutspecification to an existing sub-label, it is intended to refer to allsuch multiple similar components.

FIG. 1 is a generalized schematic diagram illustrating a computersystem, in accordance with various embodiments.

FIG. 2 is a block diagram illustrating a passive optical network, inaccordance with various embodiments.

FIGS. 3-5 illustrate network impairments at various locations in thenetwork of FIG. 2.

FIG. 6 is a process flow diagram illustrating a method of estimating alocation of an impairment in a network, in accordance with variousembodiments.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

While various aspects and features of certain embodiments have beensummarized above, the following detailed description illustrates a fewexemplary embodiments in further detail to enable one of skill in theart to practice such embodiments. The described examples are providedfor illustrative purposes and are not intended to limit the scope of theinvention.

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the described embodiments. It will be apparent to oneskilled in the art, however, that other embodiments of the presentinvention may be practiced without some of these specific details. Inother instances, certain structures and devices are shown in blockdiagram form. Several embodiments are described herein, and whilevarious features are ascribed to different embodiments, it should beappreciated that the features described with respect to one embodimentmay be incorporated with other embodiments as well. By the same token,however, no single feature or features of any described embodimentshould be considered essential to every embodiment of the invention, asother embodiments of the invention may omit such features.

Unless otherwise indicated, all numbers used herein to expressquantities, dimensions, and so forth used should be understood as beingmodified in all instances by the term “about.” In this application, theuse of the singular includes the plural unless specifically statedotherwise, and use of the terms “and” and “or” means “and/or” unlessotherwise indicated. Moreover, the use of the term “including,” as wellas other forms, such as “includes” and “included,” should be considerednon-exclusive. Also, terms such as “element” or “component” encompassboth elements and components comprising one unit and elements andcomponents that comprise more than one unit, unless specifically statedotherwise.

Although the various figures and embodiments described below aredirected to Passive Optical Networks (“PONs”), the various embodimentsare not so limited, and may be applicable to any suitable networkincluding, without limitation, non-PONs optical networks, coaxial cablenetworks, or any other suitable communications network, and the like.

Various embodiments of the concept of fiber impairment isolation mightrely on network equipment to send out a so-called dying gasp as itdetects a sudden drop in received optical power at short time scales(likely less than 1 second). As another aspect, some embodiments caninclude a supervisory function to analyze aspects of the dying gasp withthe goal to determine fiber segments associated with a fiber impairmentand an estimate of the location of an impairment within a fiber segment.Embodiments can include devices that can provide a dying gasp, devicesand/or systems that can collect and interpret dying gasp information,and methods of providing, collecting, and/or interpreting dying gaspinformation.

This concept does not rely on dedicated hardware, and may offer lowerresolution than dedicated OTDRs, but has the advantage that it can beimplemented entirely in software and therefore resulting in lower costs.The dying gasp fiber impairment detection method thus has the potentialof a much lower cost implementation. This technology can be employed ina wide variety of applications, including without limitation any type ofPassive Optical Network (“PON”) type of technology as well as variationsthereof. Examples include, but are not limited to, ITU-T APON, BPON,GPON, NG-PON1, NG-PON2, XG-PON1, XG-PON2, IEEE EPON, GE-PON (1 Gbps, 10Gbps variants and faster, should these ever emerge), RF over Glass(“RFoG”), Ethernet PON over Coax (“EPoC”), Fiber in Gas (“FiG”), or thelike. Any vendor of PON products could potentially implement the dyinggasp fiber fault detection mechanism. Any operator who deploys PONequipment could potentially deploy this technology as well. The basiclayout of a generic PON architecture is shown, for example, in FIG. 2.

More specifically, certain embodiments utilize the “dying gasp” ofnetwork equipment in a PON system (Passive Optical Network) to providefiber impairment identification (e.g., segment identification orapproximate location within segment). An application of the dying gaspis described herein beyond merely using a dying gasp to detect equipmentfaults (i.e., a simple determination whether equipment is faulty or not)in routers, fiber-optic and other types of cables, and other networkequipment (although that is possible in certain embodiments as well). Inan aspect, certain embodiments use the time stamp and/or otherinformation in the dying gasp in conjunction with an Operations SupportSystem (“OSS”) to provide a location estimation of a fiber impairment.At least two levels of accuracy are conceivable in accordance withdifferent embodiments: (1) Determination of fiber impairment location byfiber segment (e.g., feeder, distribution, drop, etc.) by takingadvantage of information about the dying gasp signal's origininformation; and (2) Estimation of fiber impairment location within asegment by taking advantage of timing information contained within thedying gasp.

In an aspect, by correlating information about dying gasp events ofvarious network elements at the Operations Support System (“OSS”) levelor some other supervisory software layer or system abstraction level, anoperator could gain considerable information about the location of afiber, connector or splicing impairment, or other type of Outside Plant(“OSP”) impairment, without requiring potentially costly, complex andresource-intensive hardware such as dedicated OTDR units. Such networkelements could include (but are not limited to): (a) ONT—Optical NetworkTerminals; (b) ONU—Optical Network Units; (c) OLT—Optical LineTerminals. Types of analysis that could be performed by variousembodiments include, but are not limited to, the following: (1)Receiving a dying gasp of only a single ONT/ONU would indicate animpairment in the fiber drop to a specific subscriber; (2) Receivingdying gasps of multiple ONTs/ONUs simultaneously or near simultaneouslymight indicate a fiber impairment in the distribution to the PONsplitter; and (3) Receiving a dying gasp from an OLT would indicate afiber fault in the backhaul from the OLT. Examples of these techniquesare described in further detail below in the context of FIGS. 3-5.

In other embodiments, additional information might be extracted fromvarious aspects of the dying gasp information available at variousprotocol levels (e.g., absolute time stamp, flight time, etc.),including information that might be added as the dying gasp propagatesthrough various protocol layers, network elements and system hardware.Various embodiments might also collect data from additional sources ofinformation related to the dying gasp, as well as additional levels ofanalysis and impairment location that could be derived from suchinformation. The dying gasp, in aspects of certain embodiments, could begenerated by network elements based on real-time observation of theoptical receiver power at sufficiently fine-grained time intervals.

Some embodiments might feature additional functionality. For instance,in some implementations, the system might be configured tocross-reference the dying gasp signal with a carrier's databases. Bycross-referencing the dying gasp signal with a carrier's existingdatabases containing information about fiber routes and length ofindividual segments at the OSS or Management System level, additionaldetail about fault location and fiber route can be made available. Bycombining time stamps and dying gasp information with known lengths ofdeployed fiber segments, the system's accuracy of locating potentialfiber faults can be improved.

Additionally and/or alternatively, some embodiments might provideadditional accuracy improvement via absolute or cyclical time stamps.Merely by way of example, by inserting an absolute or cyclical timestamp at the transmitter side, additional accuracy can be gained bycorrelating time stamps with time of flight information and knownlengths of fiber links. The size of a cyclical counter or cyclical timestamp (in bits) might depend on the desired fault location accuracy andthe desired reoccurrence period. For example, a 32-bit counter withmicrosecond resolution (one count every microsecond) might turn overevery 1 hour and 12 minutes. A 64-bit counter with nanosecond resolution(one count every nanosecond) might turn over approximately once every585 years. As mentioned above, a nanosecond temporal resolution might besufficient to resolve spatial resolution down to approximately 20 cm.

Furthermore, although the concept of a dying gasp is being explored inthe context of a new, yet to be finalized NG-PON2 standard, it couldretroactively be applied to the other PON standards, should the dyinggasp ever be added to these specifications in some sort of appendix oraddendum. Alternatively, manufacturers could choose to implement a dyinggasp or similar kind of functionality on top of any of the existing PONstandards, without affecting standards compatibility. In this case, thedying gasp functionality described herein might be applicable as well.Other PON standards to which this technology could apply might include(but are not limited to) the ITU-T APON, BPON, GPON, NG-PON1specifications, the IEEE EPON/GE-PON, and the like.

To the extent that other non-PON or non-optical media basedcommunications standards and/or protocols rely on transmission mediathat do not experience immediate faults (i.e., that might experiencedegradation over an identifiable period), the techniques describedherein might also be applicable. For example, the various embodimentsmight be applicable to the Cable-/DOCSIS-specific RFoG and EPoCspecifications, which might be based on co-axial cable or other cabletype transmission media. Furthermore, this technology could apply to FiG(Fiber in Gas) deployments as well. Moreover, the use of a dying gasp asdiscussed here is also applicable to Active Ethernet architectures andpotentially several forms of Backhaul architectures. Although currentdiscussion in the field (e.g., as part of the emerging FSAN NG-PON2standard (Next-Generation 2 Passive Optical Network)) might be directedto dying gasps indicating failure to routing devices, or other relayingcomponents in the PON, such discussions do not cover dying gaspsindicating failure of the transmission media between these routingdevices or other relaying components in the PON. In fact, the variousembodiments described herein supplement the current developments in theemerging FSAN NG-PON2 standard, and the like.

The accuracy of the time stamp information on the dying gasps caninfluence the degree of spatial resolution for impairment isolation arepossible. Merely by way of example, in some cases, resolution in the 20cm range might require time accuracy within 1 nanosecond. In othercases, resolution in the 200 m range might require time accuracy within1 microsecond. The degree of time accuracy might depend on the networkelements themselves.

It is important to note that using the dying gasp need not necessarilyreplace the use of dedicated OTDR hardware (regarding impairmentisolation). In many ways, these items could be seen as complementary. Insome aspects, the techniques described herein can be seen as a firstorder software-driven approach to impairment isolation. Dedicated OTDRhardware (whether provided in handheld units for field or repairtechnicians) or integrated in equipment that carriers deploy mightprovide additional information about fiber impairments as welladditional accuracy in fiber fault location.

A significance of the techniques and embodiments described herein mightinclude a potential to reduce operational expenses (“OPEX”) (e.g.,maintenance costs, etc.) by simplifying troubleshooting and faultdetection in the fiber access network, a potential to reduce (“CAPEX”)(e.g., infrastructure costs, etc.) in cases where carriers do notrequire added precision of dedicated OTDR hardware. An example of such ascenario where carriers do not require added precision of dedicated OTDRhardware might include a carrier with a large amount of aerial OutsidePlant (OSP). In such cases, the sources of fiber faults may often beplainly visible, e.g., fallen pole, branch, or tree, and a roughlocation of the fiber fault by fiber segment may be entirely sufficient.

FIG. 1 provides a schematic illustration of one embodiment of a computersystem 100 that can perform the methods provided by various otherembodiments, as described herein, and/or can function as an OperationsSupport System, a network element, and/or the like. It should be notedthat FIG. 1 is meant only to provide a generalized illustration ofvarious components, of which one or more (or none) of each may beutilized as appropriate. FIG. 1, therefore, broadly illustrates howindividual system elements may be implemented in a relatively separatedor relatively more integrated manner.

The computer system 100 is shown comprising hardware elements that canbe electrically coupled via a bus 105 (or may otherwise be incommunication, as appropriate). The hardware elements may include one ormore processors 110, including without limitation one or moregeneral-purpose processors and/or one or more special-purpose processors(such as digital signal processing chips, graphics accelerationprocessors, and/or the like); one or more input devices 115, which caninclude without limitation a mouse, a keyboard and/or the like; and oneor more output devices 120, which can include without limitation adisplay device, a printer and/or the like.

The computer system 100 may further include (and/or be in communicationwith) one or more storage devices 125, which can comprise, withoutlimitation, local and/or network accessible storage, and/or can include,without limitation, a disk drive, a drive array, an optical storagedevice, solid-state storage device such as a random access memory(“RAM”) and/or a read-only memory (“ROM”), which can be programmable,flash-updateable and/or the like. Such storage devices may be configuredto implement any appropriate data stores, including without limitation,various file systems, database structures, and/or the like.

The computer system 100 might also include a communications subsystem130, which can include without limitation a modem, a network card(wireless or wired), an infra-red communication device, a wirelesscommunication device and/or chipset (such as a Bluetooth™ device, an802.11 device, a WiFi device, a WiMax device, a WWAN device, cellularcommunication facilities, etc.), and/or the like. The communicationssubsystem 130 may permit data to be exchanged with a network (such asthe network described below, to name one example), with other computersystems, and/or with any other devices described herein. In manyembodiments, the computer system 100 will further comprise a workingmemory 135, which can include a RAM or ROM device, as described above.

The computer system 100 also may comprise software elements, shown asbeing currently located within the working memory 135, including anoperating system 140, device drivers, executable libraries, and/or othercode, such as one or more application programs 145, which may comprisecomputer programs provided by various embodiments, and/or may bedesigned to implement methods, and/or configure systems, provided byother embodiments, as described herein. Merely by way of example, one ormore procedures described with respect to the method(s) discussed abovemight be implemented as code and/or instructions executable by acomputer (and/or a processor within a computer); in an aspect, then,such code and/or instructions can be used to configure and/or adapt ageneral purpose computer (or other device) to perform one or moreoperations in accordance with the described methods.

A set of these instructions and/or code might be encoded and/or storedon a non-transitory computer readable storage medium, such as thestorage device(s) 125 described above. In some cases, the storage mediummight be incorporated within a computer system, such as the system 100.In other embodiments, the storage medium might be separate from acomputer system (i.e., a removable medium, such as a compact disc,etc.), and/or provided in an installation package, such that the storagemedium can be used to program, configure and/or adapt a general purposecomputer with the instructions/code stored thereon. These instructionsmight take the form of executable code, which is executable by thecomputer system 100 and/or might take the form of source and/orinstallable code, which, upon compilation and/or installation on thecomputer system 100 (e.g., using any of a variety of generally availablecompilers, installation programs, compression/decompression utilities,etc.) then takes the form of executable code.

It will be apparent to those skilled in the art that substantialvariations may be made in accordance with specific requirements. Forexample, customized hardware (such as programmable logic controllers,field-programmable gate arrays, application-specific integratedcircuits, and/or the like) might also be used, and/or particularelements might be implemented in hardware, software (including portablesoftware, such as applets, etc.), or both. Further, connection to othercomputing devices such as network input/output devices may be employed.

As mentioned above, in one aspect, some embodiments may employ acomputer system (such as the computer system 100) to perform methods inaccordance with various embodiments of the invention. According to a setof embodiments, some or all of the procedures of such methods areperformed by the computer system 100 in response to processor 110executing one or more sequences of one or more instructions (which mightbe incorporated into the operating system 140 and/or other code, such asan application program 145) contained in the working memory 135. Suchinstructions may be read into the working memory 135 from anothercomputer readable medium, such as one or more of the storage device(s)125. Merely by way of example, execution of the sequences ofinstructions contained in the working memory 135 might cause theprocessor(s) 110 to perform one or more procedures of the methodsdescribed herein.

The terms “machine readable medium” and “computer readable medium,” asused herein, refer to any medium that participates in providing datathat causes a machine to operate in a specific fashion. In an embodimentimplemented using the computer system 100, various computer readablemedia might be involved in providing instructions/code to processor(s)110 for execution and/or might be used to store and/or carry suchinstructions/code (e.g., as signals). In many implementations, acomputer readable medium is a non-transitory, physical and/or tangiblestorage medium. Such a medium may take many forms, including but notlimited to, non-volatile media, volatile media, and transmission media.Non-volatile media includes, for example, optical and/or magnetic disks,such as the storage device(s) 125. Volatile media includes, withoutlimitation, dynamic memory, such as the working memory 135. Transmissionmedia includes, without limitation, coaxial cables, copper wire andfiber optics, including the wires that comprise the bus 105, as well asthe various components of the communication subsystem 130 (and/or themedia by which the communications subsystem 130 provides communicationwith other devices). Hence, transmission media can also take the form ofwaves (including without limitation radio, acoustic and/or light waves,such as those generated during radio-wave and infra-red datacommunications).

Common forms of physical and/or tangible computer readable mediainclude, for example, a floppy disk, a flexible disk, a hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chipor cartridge, a carrier wave as described hereinafter, or any othermedium from which a computer can read instructions and/or code.

Various forms of computer readable media may be involved in carrying oneor more sequences of one or more instructions to the processor(s) 110for execution. Merely by way of example, the instructions may initiallybe carried on a magnetic disk and/or optical disc of a remote computer.A remote computer might load the instructions into its dynamic memoryand send the instructions as signals over a transmission medium to bereceived and/or executed by the computer system 100. These signals,which might be in the form of electromagnetic signals, acoustic signals,optical signals and/or the like, are all examples of carrier waves onwhich instructions can be encoded, in accordance with variousembodiments of the invention.

The communications subsystem 130 (and/or components thereof) generallywill receive the signals, and the bus 105 then might carry the signals(and/or the data, instructions, etc. carried by the signals) to theworking memory 135, from which the processor(s) 105 retrieves andexecutes the instructions. The instructions received by the workingmemory 135 may optionally be stored on a storage device 125 eitherbefore or after execution by the processor(s) 110.

Turning to FIG. 2, which is a general schematic diagram illustrating abasic PON system 200, in accordance with various embodiments. In FIG. 2,PON system 200 might comprise a plurality of optical network terminals(“ONT”) 205, a plurality of passive optical splitters 210, and anoptical line terminal (“OLT”) 215. The plurality of ONT 205 mightcomprise ONTs 205 a-205 n. Although only nine ONTs are shown in FIG. 2,any suitable number may be implemented. The plurality of passive opticalsplitters 210 might comprise splitters 210 a-210 n. Although only threesplitters are shown in FIG. 2, any suitable number may be implemented.Moreover, although only four ONTs 205 are shown coupled to each splitter210, any suitable number of ONTs 205 may be coupled to each splitter210. Although only one OLT 215 is shown, any suitable number of OLTs maybe implemented.

PON system 200 might further comprise a plurality of drop fibers 220(which might include, without limitation, drop fibers 220 a-220 n shownin FIG. 2), a plurality of distribution fibers 225 (which might include,without limitation, distribution fibers 225 a-225 n), and a backhaulfiber 230. Each of the plurality of drop fibers 220 might couple eachsplitter 210 with each ONT 205. Likewise, each of the plurality ofdistribution fibers 225 might couple each splitter 210 with the OLT 215.The backhaul fiber 230 might couple the OLT with a central office (CO)235. Although not described in detail herein, the CO typically willfeature a number of network elements for distributing signals throughoutthe PON 200; such network elements are well known to those skilled inthe art. In particular, however, the CO might feature a computer 240(which might be a standalone computer or might be part of one of thenetwork elements at the CO), which can be programmed to receive dyinggasp communications from various other network components and analyzethose communications, as described in further detail herein. (It shouldbe noted that a computer capable of performing these functions, whethera standalone computer or part of another network element, can also belocated at other locations within the PON 200, in accordance withdifferent embodiments.)

In operation, data might be transmitted via the optical fibers 220, 225,and 230 from the CO to each ONT 205 via the OLT 215 and the splitters210.

FIGS. 3-5 below illustrate faults occurring at various locations in thePON system shown in FIG. 2.

FIG. 3 is a general schematic diagram illustrating a fault in a dropfiber to an ONT in a PON system 200, in accordance with variousembodiments. In FIG. 3, a fault might occur in drop fiber 220 a betweenONT 205 a and splitter 210 a. As the fault might be occurring (whichmight include, without limitation, a cut, a bend, a break, a kink, orthe like) until all connection is lost, signal degradation might beobserved at the receiving ONT (in this case, at ONT 205 a). In responseto such detection of signal degradation, ONT 205 a might send a dyinggasp signal to the CO via splitter 210 a and OLT 215 prior to allconnection being lost due to the fault. In this manner, the CO might beable to identify that the fiber fault occurred along drop fiber 220 a,and thus can more easily and more readily initiate necessary repairs orreplacement of the broken fiber. At a suitable protocol or managementsystem level, the OSS can correlate the identification number of the ONTthat sent out the dying gasp and infer the drop fiber segment associatedwith it.

FIG. 4 is a general schematic diagram illustrating a fault in adistribution fiber to a PON splitter in a PON system 200, in accordancewith various embodiments. In FIG. 4, the fault might occur atdistribution fiber 225 a. In this case, one or more of the ONTs 205a-205 d might send a dying gasp signal to the CO via splitter 210 a andOLT 215. Upon receiving simultaneous or near simultaneous dying gaspsignals from the one or more ONTs 205 a-205 d coupled to the splitter210 a, it might be determined that the fiber fault might have occurredat distribution fiber 225 a, and appropriate repairs or replacementmight be initiated. This is especially so in the case that drop fibers220 a-220 d are located apart from each other so that a simultaneous cutof all four drop fibers 220 a-220 d is not likely to have occurred.

More particularly, a fiber fault in the distribution fiber to the PONsplitter can be determined by correlating multiple dying gasps from ONTscontained within the same group (e.g., ONT 205 a-205 d in thisparticular example). In some cases, where dying gasps of multiple ONTsmight be simultaneously or near simultaneously received, a possiblecause might be a cutting of multiple fiber lines between the multipleONTs and a splitter, which might occur due to their physical proximitywhen being laid. Such simultaneous or near simultaneous receipt of dyinggasps might appear to be a cut between the splitter and the ONTs/ONUs.One method of determining where the fault might lie might includedetermining the locations of all the ONTs sending the dying gasps, andcorrelating with timings of the dying gasps as well as proximallocations to eliminate possible types of fault (i.e., by eliminatingfaults between ONTs and splitters, eliminating faults between splittersand OLTs, not eliminating any of these possibilities, or the like). Forexample, if two optical lines are separated by some distance (e.g., arein separate neighborhoods), then they cannot have been simultaneouslycut by the same person or object.

FIG. 5 is a general schematic diagram illustrating a fault in a backhaulfiber from OLT in a PON system 200, in accordance with variousembodiments. In FIG. 5, the fault might occur at the backhaul fiber 230.In this case, the OLT 215 might send a dying gasp signal to the CO priorto all connection being lost in fiber 230. In some cases, some or all ofthe ONTs 205 coupled to the OLT 215 might each send dying gasp signalsprior to all connection being lost in backhaul fiber 230. In thismanner, the CO 235 might be able to more easily determine based on thedying gasp signals, based the identifications of the ONTs 205, OLT 215,and the like, and based on the timings of the dying gasp signals wherethe likely location of the fault might be. Accordingly, appropriaterepairs and/or replacement might be initiated.

FIG. 6 illustrates a method 600 of estimating a location of fiberimpairment in an optical network. It should be appreciated that thevarious techniques and procedures of this can be combined in anysuitable fashion, and that, while the techniques and procedures aredepicted and/or described in a certain order for purposes ofillustration, certain procedures may be reordered and/or omitted withinthe scope of various embodiments. Moreover, while the method 600 can beimplemented by (and, in some cases, is described below with respect to)the systems 100 and 200 of FIGS. 1 and 2 (or components thereof), thesemethods may also be implemented using any suitable hardwareimplementation. Similarly, while the systems 100 and 200 of FIGS. 1 and2 (and/or components thereof) can operate according to the method 600(e.g., by executing instructions embodied on a computer readablemedium), the systems 100 and 200 can also operate according to othermodes of operation and/or perform other suitable procedures.

The method 600 might comprise receiving one or more dying gaspcommunications (block 605). In some embodiments, the dying gaspcommunications might comprising at least one communication from anetwork element in a network. Examples of such communications aredescribed above. In some cases, the method 600 might further comprisedetermining that a network impairment has occurred (block 610). In manycases, this determination can be based, at least in part, on thereceived dying gasp communications. At block 615, the method 600 caninclude identifying an approximate location of the network impairment.

As noted above, a variety of techniques can be used to analyze the dyinggasp communications to identify the approximate location of theimpairment. For instance, in some cases, the method 600 might includeanalyzing relative timings of two or more dying gasp communications(block 620). Alternatively and/or additionally, as described in detailabove, each dying gasp communication might have a time stamp, andidentifying an approximate location of the network impairment mightcomprise analyzing time stamps of the one or more dying gaspcommunications (block 630). For instance, time stamps of multiplecommunications could be compared, and/or if the time stamps werecyclical, a single time stamp, along with a known location of the devicethat sent the communication, could be used to determine an approximatelocation of the impairment.

While certain features and aspects have been described with respect toexemplary embodiments, one skilled in the art will recognize thatnumerous modifications are possible. For example, the methods andprocesses described herein may be implemented using hardware components,software components, and/or any combination thereof. Further, whilevarious methods and processes described herein may be described withrespect to particular structural and/or functional components for easeof description, methods provided by various embodiments are not limitedto any particular structural and/or functional architecture but insteadcan be implemented on any suitable hardware, firmware and/or softwareconfiguration. Similarly, while certain functionality is ascribed tocertain system components, unless the context dictates otherwise, thisfunctionality can be distributed among various other system componentsin accordance with the several embodiments.

Moreover, while the procedures of the methods and processes describedherein are described in a particular order for ease of description,unless the context dictates otherwise, various procedures may bereordered, added, and/or omitted in accordance with various embodiments.Moreover, the procedures described with respect to one method or processmay be incorporated within other described methods or processes;likewise, system components described according to a particularstructural architecture and/or with respect to one system may beorganized in alternative structural architectures and/or incorporatedwithin other described systems. Hence, while various embodiments aredescribed with—or without—certain features for ease of description andto illustrate exemplary aspects of those embodiments, the variouscomponents and/or features described herein with respect to a particularembodiment can be substituted, added and/or subtracted from among otherdescribed embodiments, unless the context dictates otherwise.Consequently, although several exemplary embodiments are describedabove, it will be appreciated that the invention is intended to coverall modifications and equivalents within the scope of the followingclaims.

What is claimed is:
 1. A method, comprising: receiving, at a computer,one or more dying gasp communications, the one or more dying gaspcommunications comprising at least one communication from an opticalnetwork terminal (“ONT”) at a subscriber premises, wherein the dyinggasp communications are sent based upon a detection of a sudden drop inat least one of received power or resolution; determining, at thecomputer and based at least in part on the one or more dying gaspcommunications, that a network impairment has occurred in an opticalfiber in a network serving the ONT; and identifying, at the computer andbased at least in part on an analysis of information contained withinthe one or more dying gasp communications, an approximate location ofthe network impairment, wherein an approximate location of the networkimpairment is determined based on a number of a plurality of dying gaspcommunications received by the computer.
 2. The method of claim 1,wherein the one or more dying gasp communications comprise a pluralityof dying gasp communications from a plurality of ONT and whereinidentifying an approximate location of the network impairment comprisesidentifying that the network impairment has occurred in a distributionline to a splitter serving the plurality of ONT.
 3. The method of claim1, wherein the one or more dying gasp communications consist of one ormore dying gasp communications from the ONT, and wherein identifying anapproximate location of the network impairment comprises identifyingthat the network impairment has occurred in a fiber drop to thesubscriber premises.
 4. The method of claim 1, wherein the one or moredying gasp communications further comprise a dying gasp communicationfrom an optical line terminal (“OLT”), and wherein identifying anapproximate location of the network impairment comprises identifyingthat the network impairment has occurred in a backhaul from the OLT to acentral office.
 5. The method of claim 1, wherein the one or more dyinggasp communications comprise a plurality of dying gasp communications,the plurality of dying gasp communications comprising at least onecommunication from each of a plurality of network elements in a passiveoptical network, the plurality of network elements comprising the ONT.6. The method of claim 5, further comprising analyzing timings of theplurality of dying gasp communications to identify an approximatelocation of the network impairment.
 7. The method of claim 1, whereineach of the one or more of dying gasp communications comprises a timestamp and wherein the method further comprises analyzing time stamps ofthe one or more dying gasp communications to identify an approximatelocation of the network impairment.
 8. The method of claim 7, furthercomprising comparing time stamps of two or more dying gaspcommunications.
 9. The method of claim 7, wherein the time stampscomprise one or more time stamps associated with known lengths ofdeployed fiber segments.
 10. The method of claim 7, wherein each timestamp is a cyclical time stamp.
 11. The method of claim 10, wherein eachtime stamp is a counter.
 12. The method of claim 11, wherein the countercomprises a specified number of bits.
 13. The method of claim 11,wherein the counter has a specified resolution.
 14. The method of claim1, wherein the network is a passive optical network (“PON”).
 15. Asystem for estimating a location of fiber impairment in an opticalnetwork, the system comprising: a computer system comprising: one ormore processors; and a non-transitory computer readable medium incommunication with the one or more processors, the computer readablemedium having encoded thereon a set of instructions executable by thecomputer system to: receive one or more dying gasp communications,including at least one dying gasp communication from an optical networkterminal (“ONT”) at a subscriber premises, wherein the dying gaspcommunications are sent based upon a detection of a sudden drop in atleast one of received power or resolution; determine, based at least inpart on the one or more dying gasp communications, that a networkimpairment has occurred in a transmission medium in a network; identify,based at least in part on an analysis of information contained withinthe one or more dying gasp communications, an approximate location ofthe network impairment, wherein an approximate location of the networkimpairment is determined based on a number of a plurality of dying gaspcommunications received by the computer; and one or more networkelements in communication with the computer system, the one or morenetwork elements comprising the ONT, wherein each of the one or morenetwork elements are configured to generate dying gasp communicationsindicating network impairments; wherein the one or more dying gaspcommunications comprise at least one communication from at least one ofthe one or more network elements.
 16. The system of claim 15, whereinthe one or more dying gasp communications comprise a plurality of dyinggasp communications from a plurality of ONT and wherein identifying anapproximate location of the network impairment comprises identifyingthat the network impairment has occurred in a distribution line to asplitter serving the plurality of ONT.
 17. The system of claim 15,wherein the one or more network elements comprise at least one opticalline terminal (“OLT”), and wherein identifying an approximate locationof the network impairment comprises identifying that the networkimpairment has occurred in a backhaul from the at least one OLT to acentral office.
 18. The system of claim 15, wherein the set ofinstructions further comprise instructions to analyze timings of theplurality of dying gasp communications to identify an approximatelocation of the network impairment.
 19. The system of claim 15, whereineach of the one or more of dying gasp communications comprises a timestamp, and wherein the set of instructions further comprise instructionsto analyze time stamps of the one or more dying gasp communications toidentify an approximate location of the network impairment.
 20. Thesystem of claim 15, wherein the computer system is part of a serviceprovider central office.